This invention relates to an apparatus and method for raising and supporting a building, and more particularly to such an apparatus and method in which pilings are used to support the foundation or concrete slab of a building.
Houses and other buildings are often erected on foundations or concrete slabs which are not in direct contact with load supporting underground strata, such as bedrock, or the like. If not initially constructed properly, or if soil conditions change, the foundation footing may settle, causing the foundation or slab to sag and/or crack. Unless the building is supported, or shored, continued settling may result in major structural damage or collapse of the building.
There have been several suggestions in the prior art for raising and supporting the foundation or slab of a building of this nature. For example, according to one technique the foundation or slab is lifted, or jacked up, and pilings are inserted underneath to support same. However, the pilings are often not directly supported on the bedrock, resulting in continued settling after the pilings are in place. Also, these techniques often require extensive evacuation of the basement flooring for placing the pilings under the foundation walls, which is expensive. Further, in many instances, the pilings are visible above the basement floor.
In still other prior art techniques utilizing pilings, a single hydraulically actuated system is used for each piling, requiring the use of a relatively high pressure hydraulic system, which is expensive and cumbersome to use. Also, if the pilings are lifted individually, the structure of the foundation or slab becomes uneven which causes additional potential problems.
In co-pending, application, Ser. No. 766,775, filed Aug. 16, 1985, now U.S. Pat. No. 4,673,315, of which the present applicant is a co-inventor, these problems with the prior art techniques are overcome in an apparatus that features a hydraulic ram system connected between a clamp secured to the upper portion of the piling and a guide means connected to the lifting arm that extends under the foundation or slab of the building. Upon retraction of the hydraulic ram system, the pipe assembly is driven into the ground until it encounters a predetermined resistance after which the ram assembly is actuated again to raise the foundation or slab a predetermined distance.
As a result, the pilings are supported directly on the bedrock and are invisible after the method is completed, even though only minimum excavation of the ground surrounding the foundation is required. In addition, this system eliminates the need for high pressure ram devices while permitting all of the piling assemblies associated with the particular foundation to be raised at once.